Graphics subsystems commonly include a graphics processing unit that generates frame data for storage in a frame buffer prior to display. Typically, with graphics processing units, many components (display, graphics, memory, etc.) share a same power rail within a graphics subsystem. Even if some of the components are not being used, there is a large power drain on a user's system. In the case of memory, even if memory is not being used, memory devices cause a large power drain on the user's system.
Display requires power at all times. Even if a user is not interacting with the system, the screen must be active and refreshed every frame. This scenario is very common and is a large contributor to decreased battery life of the user's system. Because the display typically shares the same power rail as other components within the graphics subsystem, the power rail cannot be completely shut off for power savings. It would be advantageous to power off memory devices within the graphics subsystem for the purpose of conserving the user's system power.
Some specifications have attempted to address power down of memory devices when a duplicate image frame generated by the graphics processing unit is detected. Such specifications have used a cyclic redundancy check to compare a newly generated frame to a previously generated frame in order to detect if the frames are identical. If the frames are identical, some or all of the memory devices are powered down until a newly generated frame that is not identical to the prior frames is generated by the graphics processing unit. These specifications have a multiple step method of entering a low power state comprising detecting a repeated frame, snooping the frame, entering a low power state, exiting a low power state, and displaying an updated frame. This multiple step method creates an unwanted wake up latency within the user's system due to the limited responsiveness of the solution due to the many stages involved to enter and exit power down.